This application relates to vehicle parts and more particularly to improvements in plastic door pillar covers and the method of making such covers.
It is well known that many vehicles mask the portion of the door B-pillar which is coextensive with the window so as to provide edge coverage as well as color contrast. Heretofore, covers of this type have been injection molded of a suitable plastic material. In order to achieve a high gloss finish, the molded article is either injection molded over a preformed paint film laminate inserted in the mold or painted in conventional fashion after molding with the required number of coats. This method of making the covers resulted in the formation of wall thickness greater than required because of the necessity to practice efficient mold filling procedures. The cost of providing excess material and the added cost of finishing the part created a particular need for cost effectiveness in producing the part.
Moreover, B-pillar covers are installed in a highly visible position on the vehicle. Every time a driver or passenger enters a vehicle, the driver or passenger will glance at the B-pillar. Thus, any defect on the exterior surface of the B-pillar will be noticed and will dramatically affect consumer acceptance and satisfaction. Thus, it is critical that the B-pillar cover have a very smooth exterior surface. This surface, in the automotive industry, is known as a "class A" finish. The standards for a class A finish are well known in the industry, and, in particular, are known to be very stringent. Parts having even minor cosmetic defects in the class A finish will be rejected.
While vacuum molding thin plastic parts has heretofore been performed, the present inventors have discovered that such methods suffer from inherent drawbacks in applications requiring a class A finish. Vacuum molding processes have involved creating a vacuum at a body molding surface so as to draw a thermoplastic material to the body molding surface. Vacuum orifices are formed in the body molding surface and are connected, via vacuum channels, to a vacuum source. Where the part to be molded is to be formed from relatively thin material, such as a B-pillar, drawing the surface to the body molding surface can create small vacuum dimples at the vacuum orifices. Such dimples would be visible to the eye, especially when the sun is shinning on the part, and, therefore, are unacceptable for a class A finish.